http://vg-news.ru/n/117388 , 3 October 2015 at 10:12:
“… An American military expert, a former Colonel of the U.S. army Jack Jacobs said that the United States can’t stop Russians in Syria, because Russia has de facto established a closed zone over it, blocking the access to any aircraft with the help of its air defense systems, deployed both on land and on ships of the Russian fleet in the Mediterranean.
On Friday, 2 October, Saudi news published an interview with former U.S. Colonel Jack Jacobs, who announced that the United States can’t stop the Russians in Syria, as Russia has established a “closed zone” over it. This means that any military aircraft entering the zone of hostilities, can be immediately shot down as a threat to the Russian Air and space forces.